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Mechanical Tuning of the Senses

Physical changes in the surrounding microenvironment of cells, in the absence of any other modifications, are enough to affect the way they sense touch, a UNSW Medicine research shows.

“Individual cells are exposed to so many different types of mechanical input—vibration, stretch, soft and hard stimuli. I think it’s really interesting to investigate how cells can distinguish between them,” says study lead author, Dr Kate Poole.

The team of mechanobiologists found that signals transmitted via PIEZO1—a specialised sensory protein—are shaped by changes in the roughness and stiffness of the surfaces in contact with cells. Like many proteins associated with the sense of touch, PIEZO1 is a mechanically-gated ion channel embedded in the cell membrane; the channel opens in response to mechanical forces.

The study is published in the journal ACS Nano.

“PIEZO1 is expressed in a lot of different cells and tissues—including cardiac tissue, chondrocytes in cartilage, and blood cells. We wanted to understand how it might be activated by different stimuli, enabling the protein to respond to distinct forces in different tissues,” says Dr Poole who leads a research group at Single Molecule Science in the School of Medical Sciences.

“There’s only a few different types of mechanically-activated ion channels sensing all these signals, how are they able to code and understand all of these wildly different stimuli? There’s clearly something else that helps to tune these sensors so they can distinguish all of these different sensations,” says Ms Jessica Richardson, second year PhD student, and one of the co-first authors of the paper.

To dissect out the different elements influencing signalling via PIEZO1, and other mechanically-gated ion channels, the research team use a culture system developed previously by Dr Poole and her colleagues in Germany. Cells are grown on top of elastic micropillars, the mechanical properties of which they can manipulate to mimic the types of physical conditions experienced by cells in different tissues in the body. This system allows researchers to apply mechanical stimulation directly at the contact points between the cells and their surroundings.

These findings are just a piece of the puzzle. Dr Poole explains that there is much more to learn about how cells sense their microenvironment.  

“For anyone thinking about how physical surroundings impact cellular function, these data suggest that mechanics alone can change the signal transduction pathways.”

[Feature image: Changing the mechanical properties of elastic micropillars that cells are grown on can tune mechanical signalling (right)]